四

In oracle bone script, it was written as 亖. This form is an ideogram, created in the same way as 一 (1), 二 (2), and 三 (3). With two "二" stacked vertically, it can be interpreted as "two plus two makes four."

However, starting from the bronze inscriptions, the character 四 began to be borrowed and used instead. From the seal script period onward, 四 completely replaced 亖 in common use.

The original meaning of 四 was to depict breath coming out of the mouth, and its root form is considered to be 呬 (pronounced heui, meaning "to breathe"), which includes the radical 口 (mouth). Therefore, 四 eventually replaced 亖, and 呬 came to represent the original meaning.

사방 (四方) — four directions

사면 (四面) — four sides

사계절 (四季節) — four seasons

Interestingly, the characters 一, 二, 三, and 亖 also resemble the military ranks of soldiers in South Korea.

Because 四 (four) is a homophone of 死 (death)—both pronounced sǐ in Chinese—it came to be considered unlucky in East Asian cultures (China, Korea, Japan, and Vietnam).

In Japan, this superstition also affects pronunciation: the on'yomi (Sino-Japanese reading) シ (shi), which sounds like "death," is often avoided. Instead, native Japanese readings like ヨ (yo) or ヨン (yon) are used—similar to how Koreans might read numbers as “il, i, sam, net, o...” rather than using Sino-Korean readings alone.

However, this avoidance is mainly when counting numbers in order; in compound words, the on'yomi is still commonly used.

For example:

4월 (April) = 四月

사각 (square) = 四角

Four also symbolizes stability:

- four directions (east, west, south, north);

- four seasons;

- four virtues in Confucian thought.

The character plays a major symbolic role in cosmology and spatial orientation.

The Book of Changes (易經) uses numerical symbolism, including structural divisions into fours.

The Book of Rites (禮記) mentions four cardinal orientations in ritual structure.

The formal (banker’s) numeral for four is 肆.

亖 (used from the oracle script era),

肆 and 䦉 (more complex variants).